Department of Biotechnology, Faculty of Animal Husbandry and Biotechnology, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, 3-5 Manastur Road, 400372, Cluj-Napoca, Romania.
Mol Biol Rep. 2013 Jul;40(7):4311-6. doi: 10.1007/s11033-013-2518-2. Epub 2013 May 3.
The characterization of casein polymorphism is an essential step in order to understand the genetic basis of milk quality in dairy ruminants. In this work, we report the identification of a regulatory mutation at the buffalo αs1-casein (CSN1S1) gene that alters the normal processing of the primary transcript. Sequencing of CSN1S1 cDNA from individuals harbouring this new variant revealed that its most distinctive feature is the loss of exon 6 that encodes eight amino acids between positions 35-42 of mature protein. In an effort to map the causal mutation, we sequenced a genomic region spanning exons 5-7 of the buffalo CSN1S1 gene. This experiment allowed us to establish that exon 6-skipping is produced by a G to C substitution at the first position of intron 6 that inactivates the donor splice site. This mutation can be typed by PCR-RFLP by using either TaaI or Bpu10I diagnostic restriction enzymes, and it has a frequency of 0.18 in Romanian buffaloes. This exon skipping phenomenon is the first one described in buffalo CSN1S1 locus.
对酪蛋白多态性进行特征描述是了解反刍动物乳品质遗传基础的必要步骤。在这项工作中，我们报告了在水牛αs1-酪蛋白（CSN1S1）基因中发现了一个调节突变，该突变改变了初级转录本的正常加工。对携带这种新变体的个体的 CSN1S1 cDNA 进行测序表明，其最显著的特征是丢失了编码成熟蛋白第 35-42 位之间 8 个氨基酸的外显子 6。为了定位致病突变，我们对水牛 CSN1S1 基因的 5-7 号外显子跨越的基因组区域进行了测序。该实验使我们能够确定，外显子 6 跳跃是由第 6 号内含子第一位的 G 到 C 取代产生的，该取代使供体位点失活。该突变可以通过使用 TaaI 或 Bpu10I 诊断性限制酶的 PCR-RFLP 进行分型，其在罗马尼亚水牛中的频率为 0.18。这种外显子跳跃现象是在水牛 CSN1S1 基因座中首次描述的。
